The Field of the Invention
This invention relates to a process for providing metal complexed dyes and particularly to a process providing metal complexed dyes having a silver halide developing capability.
Metal complexed dyes which may have a silver halide developing capability are old and known to the art. Such dyes can be defined broadly by the following formula: ##STR4## where A is a benzene or naphthalene radical which includes substituted derivatives of such radicals; B is a benzene, naphthalene or a nitrogen containing heterocyclic radical such as pyrazolone or pyrimidine radicals including substituted derivatives of such radicals; R is N or CH; Y is a silver halide developing substituent; each n is O, 1 or 2; X is usually oxygen (O) but particularly if R is N, may be an oxygen containing substituent such as ##STR5## or -- alkyl --O--; Me is a metal complexing atom such as a transition metal, particularly a member of the first transition series, i.e., chromium, colbalt, nickel, iron, zinc, manganese, scandium, titanium and vanadium and, L represents a molecule or a moiety that can satisfy the coordination sphere of the Me atom and can be H.sub.2 O, CH.sub.3 NCHO-among others. Metal complexed dyes within the above formula are described in U.S. Pat. Nos. 3,551,406; 3,563,739; 3,597,200; 3,705,184; 3,752,836 and in commonly assigned U.S. Pat. Application Ser. No. 836,076 filed Sept. 23, 1977.
Particularly preferred metal complexed dyes are those described in such U.S. Pat. Nos. as 3,551,406; 3,563,739 and 3,705,184. These preferred metal complexed dyes conform to the following formula: ##STR6## where A,R,B, Me and L are as defined before and Z' is a substantially colorless bidentate ligand radical and the silver halide developing substituent (Y) is attached to the ligand radical. Especially preferred metal complexed dyes of Formula B which have enjoyed extensive commercial success in diffusion transfer photographic products and processes are the magenta chrome complexed azo dye developer and the yellow chrome complexed azomethine dye developer of the following formulae: ##STR7##
As can be seen from Formulae C and D, the bidentate ligand radical having the silver halide developing substituent, e.g., the "Y-Z'" of Formula B, is the same for both the azo and azo-methine dye. This particular "Y-Z" moiety, in its non-complexed form, is of the following formula. ##STR8## where each R' is H or a protective group that can be converted to H.
Normally in preparing chrome-complexed dye developers of Formulae B, C and D, the dye moiety, e.g., ##STR9## is reacted with a suitable chrome compound in manners known to the art. The chrome-complexed dye is then reacted with the bidentate ligand silver halide developer of Formula E to provide chrome-complexed dye developers of Formulae C and D. Usually, the bidentate ligand compound reacted with the chrome complexed dye has protective groups at the hydroxyphenyl sites and the protective groups are later removed in known manner to provide the hydroxyphenyl substituents. Details relating in ligands of Formula E and methods for making and using them can be found in U.S. Pat. Nos. 3,629,336; 3,772,368; 3,812,191; 3,903,169; 3,929,848; 3,970,616 and in commonly assigned U.S. Pat. application Ser. No. 784,933 filed Apr. 5, 1977.
The method described in U.S. Pat. No. 3,812,191 involves the preparation of a compound of Formula E of the following formula: ##STR10##
More specifically, the method of U.S. Pat. No. 3,812,191 involves the preparation of a "protected" compound of Formula F, e.g., the compound [3-(2,5-dicathyloxyphenyl) propionyl] -2- cyclopentanone and the removal of the protecting groups -- the cathyloxy groups -- to provide a compound of Formula E.
According to the method disclosed in referenced U.S. Pat. No. 3,812,191, the cathyloxy groups of the [3-(2,5-dicathyloxyphenyl) propionyl)]-2-cyclopentanone are removed by saponifying the protected compound in a substantially non-aqueous, solubilizing medium comprising a solution of an alkali metal hydroxide in an alcohol and acidifying the saponified product to a pH of between about 6.0 to about 7.0 and preferably between about 6.5 to about 7.0. The controlled acidification of the saponified product is an important factor in the method of U.S. Pat. No. 3,812,191 leading to commercially acceptable yields of compounds of Formula E. For example, if the saponified product is acidified to a pH below 6.0 and particularly to a pH below 3.0, the predominant product is not the compound of Formula E -- where each R' is H -- but rather a cyclized compound of the following formula: ##STR11## where each R.sup.2 is usually hydrogen.
Essentially then, the process of U.S. Pat. No. 3,812,191 is designed to minimize formation of compounds of Formula G and maximize formation of compounds of Formula E.
According to the invention disclosed in commonly assigned U.S. Pat. Application Ser. No. 784,933 it has been found that formation of the cyclized compound of Formula G can provide certain advantages. For example according to the process of copending application, Ser. No. 784,933, compounds of Formula F can be converted to the cyclized compounds of Formula G of high purity and then the cyclized compound can be "opened up" with acids to provide extremely pure compounds of Formula E -- where each R' is H.
The invention presents to the art a process for producing metal complexed dyes particularly of the type embraced by Formula B. Essentially, the invention involves the discovery that the cyclized compounds of Formula G can be reacted directly with metal complexed dyes to provide dye developers of the type illustrated by Formulae C and D.